CA1252012A - Treatment of tobacco - Google Patents
Treatment of tobaccoInfo
- Publication number
- CA1252012A CA1252012A CA000511538A CA511538A CA1252012A CA 1252012 A CA1252012 A CA 1252012A CA 000511538 A CA000511538 A CA 000511538A CA 511538 A CA511538 A CA 511538A CA 1252012 A CA1252012 A CA 1252012A
- Authority
- CA
- Canada
- Prior art keywords
- tobacco
- separator
- medium
- duct
- gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
- A24B—MANUFACTURE OR PREPARATION OF TOBACCO FOR SMOKING OR CHEWING; TOBACCO; SNUFF
- A24B3/00—Preparing tobacco in the factory
- A24B3/18—Other treatment of leaves, e.g. puffing, crimpling, cleaning
- A24B3/182—Puffing
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
- F26B17/10—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers
- F26B17/106—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers the drying enclosure, e.g. its axis, being substantially straight and horizontal, e.g. pneumatic drum dryers; the drying enclosure consisting of multiple substantially straight and horizontal stretches
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B3/00—Drying solid materials or objects by processes involving the application of heat
- F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
- F26B3/10—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour carrying the materials or objects to be dried with it
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Microbiology (AREA)
- Manufacture Of Tobacco Products (AREA)
- Manufacturing Of Cigar And Cigarette Tobacco (AREA)
Abstract
"Improvements Relating to the Treatment of Tobacco"
A B S T R A C T
In the expansion of tobacco, the tobacco is entrained in hot gaseous medium, separated from the gaseous medium and re-introduced and re-entrained in the gaseous medium before being once again separated from the medium.
A B S T R A C T
In the expansion of tobacco, the tobacco is entrained in hot gaseous medium, separated from the gaseous medium and re-introduced and re-entrained in the gaseous medium before being once again separated from the medium.
Description
i2~
IMPROVEMENTS RELATING TO THE TREATMENT OF TOBACCO
This invention relates to the reduction of the moisture content of particulate tobacco.
Numerous particulate tobacco drying processes have been heretofore proposed. The purpose of many of these prior proposed processes is not merely to reduce the moisture content of the tobacco, but to effect also an expansion of the tobacco particles and/or an increase in the filling power of the tobacco.
A process for drying tobacco, which process effects an increase in the filling power of the tobacco is disclosed in United Kingdom Patent Specification No.
IMPROVEMENTS RELATING TO THE TREATMENT OF TOBACCO
This invention relates to the reduction of the moisture content of particulate tobacco.
Numerous particulate tobacco drying processes have been heretofore proposed. The purpose of many of these prior proposed processes is not merely to reduce the moisture content of the tobacco, but to effect also an expansion of the tobacco particles and/or an increase in the filling power of the tobacco.
A process for drying tobacco, which process effects an increase in the filling power of the tobacco is disclosed in United Kingdom Patent Specification No.
2 004 999 A. According to this process particulate tobacco is fed into a stream of hot, high humidity air.
The air entrained tobacco particles are conveyed through a plurality of vertically disposed drying ch&mbers and interconnecting ducts. Expanded tobacco and air leaving the last of the drying chambers pass to a separator operable to separate the tobacco from the air. An earlier published specification disclosing a generally similar process is United Kingdom Patent Specification No. 957,532.
A process for drying particulate tobacco according to which the tobacco is in contact with a hot drying gas for a minimal time is disclosed in United States Patent Specification No. 4,494,556. Particulate tobacco is fed into a stream of the drying gas at a location closely ~L~5~
adjacent the point of entry of the stream into a solids-gas separator which it is stated is operable to separate the tobacco from the drying gas with a low residence time of the tobacco particLes in the separator.
In European Patent Specification No. 074 059 there is disclosed a filling power improvement process in which moist particulate tobacco is fed into a stream of hot drying gas which conveys the tobacco particles through a venturi nozzle. At the throat section of the nozzle the reduced pressure causes flash evaporation of moisture in the tobacco. This results in an expansion of the tobacco particles. From the venturi nozzle the drying gas and the tobacco entrained therewith flow through a vertically disposed drying chamber and then into a cyclone separator.
A similar process to that of Specification No.
074 059 is disclosed in United Kingdom Patent Specifica-tion No. 2 111 820 A.
In a tobacco e~pansion process disclosed in United Kingdom Patent Specification No. 1,382,839 particulate tobacco which has been subjected to a microwave field is fed into a stream of hot gas which conveys the tobacco, under the action of a first fan, to a first separator.
The tobacco separated in the first separator from the hot gas is fed into a stream of cool gas which, under the action of a second fan, conveys the tobacco to a second separator.
A particulate tobacco conditioning apparatus which is disclosed in United Kingdom Patent Specification No.
1,389,452 comprises a vibratory conveyor which extends through three treatment chambers. The conveyor is of air permeable construction and fan means is provided by operation of which a stream of hot air can be introduced into the first treatment chamber beneath the conveyor. The hot air passes up through the conveyor and the tobacco thereon, causing an agitation of the tobacco, before passing from the first treatment chamber into a pipe which conveys the air to the second treatment chamber beneath the run of the conveyor therewithin.
After passing up through the conveyor and the tobacco in the second chamber, the air is conveyed to the space beneath the run of the conveyor in the third chamber.
The air leaves the third chamber through an exhaust outlet open to atmosphere, having in the third chamber once again passed upwardly through the tobacco.
The prior proposed processes in which particulate tobacco is conveyed in a stream of gaseous medium to dry the tobacco, suffer from one or more of three defects, namely (1) an over-long and continuous exposure of the tobacco to a hot gaseous medium, (2) too intensive a heating regime and (3) after the lapse of a short acceleration period, absence of differentation in the velocity of the tobacco particles and the conveying gaseous medium. The first and second of these defects can have a deleterious effect on the tobacco and on the 5~ 2 final filling power thereof. The third defect resul-ts in a reduced rate of heat ancl mass transfer.
It is an object of the present invention -to provide a method of drying particulate tobacco whereby -the above identified defects of the prior tobacco dryin~J proposals are avoided or at least significantly diminished.
The present invention provides a me-thod of reducing the moisture con-tent of particulate tobacco, wherein particulate tobacco is fed into a stream of hot gaseous medium, said medium conveys said tobacco through a first duct to a first separator, said tobacco is separa-ted from said medium in said first separator, said medium passes from said first separator to a second duct, said tobacco is fed from said first separator into the stream of said medium flowing in said duct downstream of said first separa-tor, whereby said medium conveys said tobacco through said second duc-t to a second separator, and said tobacco is separated from said medium in said second separator.
When particulate -tobacco is treated in accordance with the present invention, the -tobacco is twice subjected to acceleration by the gaseous medium, once in the ~irs-t duct and once in the second duc-t. Intermediate its passage through the first and second ducts the tobacco is maintained for a period out of contac-t with the gaseous medium.
Preferably, delay means is employed to extend this period -to a time value greater than it would otherwise be.
~"2~,2~f-~2 Advantageously, the delay means is adjustable to provide for selection of the residence time of the tobacco particles therein.
Cut stem tobaccos, cut lamina tobaccos or blends thereof may be treated in accordance with the present invention.
The gaseous medium may be, for example, steam, air, steam and air, or nitrogen.
According to another aspect of the present invention there is provided tobacco drying apparatus comprising a first duct, a first gas-flow passage in communication at a downstream end thereof with an upstream end of said first duct, a first tobacco feed path extending to and opening into said first gas-flow passage, first separator means in communication with a downstream end of said first duct, a second duct, a second gas-flow passage in communication at a downstream end thereof with an upstream end of said second duct, a second tobacco feed path extending from said first separator means to and opening into said second gas-flow passage, a gas-flow pipe extending from said first separator means and being in communication with the upstream end of said second gas-flow passage, and second separator means in communication with the downstream end of said second duct, said first separator means being functionable to receive gaseous medium and tobacco from said first duct, to permit said gaseous medium to pass substantially absent said tobacco ~2~ 2 to said gas-flow pipe and to permit said tobacco to pass substantially absent said ~aseous medium to said second tobacco feed path. Pre~erably, variable residence time means is disposed in the second tobacco feed path and is operable to adjust selectively the residence time of tobacco particles in the second feed path.
Apparatus may be provided in accordance with the present invention which apparatus is comparatively inexpensive, compact, simple in construction and readily operable.
In order that the present invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the diagrammatic drawing hereof, which shows a tobacco expansion apparatus.
~5 The tobacco expansion apparatus shown in the dia-grammatic drawing comprises a first tobacco feeder, generally designated 1, which provides a first tobacco feed path. The feeder 1 is comprised of a rotary airlock 2 fitted with an inlet hopper 3 and a downwardly e~tending outlet pipe 4. A feed conveyor 5 is operable to feed particulate tobacco to the inlet hopper 3. At its lower end, the outlet pipe 4 opens into a first gas-flow passage in the form of a short length of piping 6. At an outlet end theeof the piping 6 communicates with an upwardly inclined expansion pipe 7 which provides a first duct.
At its higher end, the pipe 7 opens into the interior of a casing 8 of a first separator 9. Extending ~52~ Z
across the interior of the casing 8, so as to divide the interior into two sections, is a mesh screen 10. A
short outlet pipe 11 extends downwardly from a lowermost location of the separator 9. The pipe 11 serves to intercommunicate that section of the interior of the casing 8 which is to the side of the mesh screen 10 at which the pipe 7 opens into the casing 8, with a second tobacco feeder, generally designated 12.
The second tobacco feeder 12, which provides a second tobacco feed path, is comprised of a rotary airlock 13 and an outlet pipe 14 which e~tends downwardly from the airlock 13 and opens into a second gas-flow passage in the form of a short length of piping 15.
To the side of the mesh screen 10 of the separator 15 9 remote the pipes 7 and 11 a further outlet pipe 16 serves to intercommunicate the interior of the casing 8 with the inlet of a centrifugal fan 17. A gas-flow pipe 18 extends from the outlet of the fan 17 to an inlet end of the piping 15.
The outlet end of the piping 15 communicates with an upwardly inclined expansion pipe 19 which provides a second duct.
At its higher end, the pipe 19 opens into the interior of a casing 20 of a second separator 21. The separator 21 is of similar construction to the separator 9 and comprises a mesh screen 22 dividing the interior of the casing 20 into two sections, a short outlet pipe S~ 2 23 to the same side of the mesh 22 as is the opening of the pipe 19, and a further outlet pipe 24 to the other side of the mesh screen 22. The outlet pipe 23 serves to intercommunicate the interior of the casing 20 with a rotary airlock 25 from which there downwardly extends a discharge pipe 26.
The outlet pipe 24 serves to intercommunicate the interior of the casing 20 of the separator 21 with the inlet of a centrifugal fan 27. From the outlet of the fan 27 a pipe 28 extends, first downwardly and then horizontally, to a heater 29. An e~haust pipe 30 branches from the pipe 28 and a steam make-up pipe 31 communicates with the pipe 28 at a location intermediate the branching location of the pipe 30 and the heater 29.
The heater 29, which may, -for e~ample, be gas or oil fired, is operable to heat the steam/air mixture (hereinafter referred to a~ "gaseous medium") delivered from the pipe 2~. An outlet pipe 32 serves to convey gaseous medium which has been heated in the heater 29 to the inlet end of the piping 6.
In operation of the apparatus to expand particulate tobacco, cut stem tobacco for e~ample, gaseous medium flow is established in the apparatus aided by operation of the centrifugal fans 17 and 27. The tobacco is fed to the inlet hopper 3 from the feed conveyor 5 and passes through the rotary airlock 2, driven by rotary drive means (not shown), and the outlet pipe 4 to the piping 6.
In the piping 6 the tobacco particles are entrained by-the gaseous medium which is conveyed -to the piping 6 in the pipe 32 extending from the heater 29. It is preferable, in order to promote the entrainment of the tobacco particles, for the interior of the piping 6 to be of a venturi configurat:ion with the pipe 4 opening at the throat thereof.
The gasous medium conveys the tobacco particles along the pipe 7 to the first separator 9, the mesh screen 10 of which permits passage of the gaseous medium to the fan 17 but constrains the tobacco particles to pass down-wardly to the air~ock 13. The tobacco passas through the airlock 13, driven by rotary drive means (not shown), and through the outlet pipe 14 to the piping 1~5. In the piping 15 the tobacco particles are entrained by gaseous medium which is conveyed to the piping 15, preferably without the gaseous medium being subjected to re-heating, in the gas-flow pipe 18 extending from the fan 17.
The gaseous medium conveys the tobacco particles along the pipe 19 to the second separator 21, the mesh screen 22 of which permits passage of the gaseous medium to the fan 27 but constrains the tobacco particles to pass downwardly to the airlock 25, driven by rotary drive means (not shown). The tobacco particles pass from the airlock 25 through the discharge pipe 26 to a receptacle or a conveyor (not shown). The tobacco particles are subsequently subjected to a coolin~ step ~L~52~
which is in accordance with established practice and which, for the sake of simplicity, is not further discussed.
From the fan 27 the gaseous medium passes along the pipe 28 to the heater 29 in which the heat given up by the gaseous medium during -the passage thereof through the apparatus is replaced. Gases and water vapour generated in the apparatus and air which has entered the apparatus through the airlocks 2~ 13 and 25 are removed via the exhaust pipe 30. Make-up steam can be supplied, from a steam generator (not shown), via the make-up pipe 31.
The apparatus which is comparatively inexpensive, compact and simple in construction and operation, provides a very efficient means of drying and expanding particulate tobacco. As soon as the tobacco enters the p,ping 6, the tobacco particles are accelerated by the gaseous medium.
Thus as the particles are conveyed up the pipe 7 by the gaseous medium, the velocity differential between the tobacco particles and the gaseous medium diminishes.
However, the separation of the tobacco and the gaseous medium effected in the separator 9 and the reintroduction of the tobacco into the gaseous medium in piping 15 means that the process of acceleration of the tobacco is repeated. This means that there is a velocity differential between the tobacco and the gaseous medium over a greater period of time than would be the case if the tobacco ~2~2 passed along a single, straight expansion pipe, of a length equivalent to the combined lengths of pipes 7 and 19, without an intermediate reacceleration. Thus in comparison with an apparatus comprising a single expansion pipe of equivalent length, the apparatus shown in the drawing effects heat and mass transfer at enhanced efficiency levels.
Moreover, the separation of the tobacco particles from the hot gaseous medium intermediate the passage of the particles in contact with the medium in the first and second expansion pipes 7, 19 permits a degree of moisture migration to take place in each particle towards the surface of the particle and ensures that the rigour of the heating regime to which the particles are subjected is less than would otherwise be the case. This has benefits in terms of the filling power of the tobacco which passes from the apparatus through discharge pipe 26.
In order to obtain adjustment of the residence time of the tobacco in the airlock 13, the drive means thereof is preferably of a variable speed type.
In order to minimise the overall time during which the tobacco is in contact with the hot gaseous medium, which overall time may be, for example, of the order of one second, it is important that the mean residence time of the tobacco particles in the separators is short and that there is only a narrow statistical distribution of residence times of the particles in the separators.
.~ 252~
This requirement is met by the separators 9 and 21 which are of a type supplied by Hambro Machinery Limited, Nottingham, England. Cyclone separators would meet the requirement less well.
Although, as above described, the apparatus is - operated without re-heating of the gaseous medium in its passage from the fan 17 to the piping 16, it is conceiv-able to provide such a re-heating step.
As an alternative to the tobacco passing via the pipe 14 directly from the airlock 13 to the piping 15, it may be fed from the airlock 13 onto a conveyor (not shown), from which the tobacco passes into the piping 15 through a further airlock (not shown). In such case the conveyor and/or the further airlock can provide a delay function in addition to, or in place of, that of the airlock 13. The conveyor and/or the further airlock may be provided with variable speed drive means.
The air entrained tobacco particles are conveyed through a plurality of vertically disposed drying ch&mbers and interconnecting ducts. Expanded tobacco and air leaving the last of the drying chambers pass to a separator operable to separate the tobacco from the air. An earlier published specification disclosing a generally similar process is United Kingdom Patent Specification No. 957,532.
A process for drying particulate tobacco according to which the tobacco is in contact with a hot drying gas for a minimal time is disclosed in United States Patent Specification No. 4,494,556. Particulate tobacco is fed into a stream of the drying gas at a location closely ~L~5~
adjacent the point of entry of the stream into a solids-gas separator which it is stated is operable to separate the tobacco from the drying gas with a low residence time of the tobacco particLes in the separator.
In European Patent Specification No. 074 059 there is disclosed a filling power improvement process in which moist particulate tobacco is fed into a stream of hot drying gas which conveys the tobacco particles through a venturi nozzle. At the throat section of the nozzle the reduced pressure causes flash evaporation of moisture in the tobacco. This results in an expansion of the tobacco particles. From the venturi nozzle the drying gas and the tobacco entrained therewith flow through a vertically disposed drying chamber and then into a cyclone separator.
A similar process to that of Specification No.
074 059 is disclosed in United Kingdom Patent Specifica-tion No. 2 111 820 A.
In a tobacco e~pansion process disclosed in United Kingdom Patent Specification No. 1,382,839 particulate tobacco which has been subjected to a microwave field is fed into a stream of hot gas which conveys the tobacco, under the action of a first fan, to a first separator.
The tobacco separated in the first separator from the hot gas is fed into a stream of cool gas which, under the action of a second fan, conveys the tobacco to a second separator.
A particulate tobacco conditioning apparatus which is disclosed in United Kingdom Patent Specification No.
1,389,452 comprises a vibratory conveyor which extends through three treatment chambers. The conveyor is of air permeable construction and fan means is provided by operation of which a stream of hot air can be introduced into the first treatment chamber beneath the conveyor. The hot air passes up through the conveyor and the tobacco thereon, causing an agitation of the tobacco, before passing from the first treatment chamber into a pipe which conveys the air to the second treatment chamber beneath the run of the conveyor therewithin.
After passing up through the conveyor and the tobacco in the second chamber, the air is conveyed to the space beneath the run of the conveyor in the third chamber.
The air leaves the third chamber through an exhaust outlet open to atmosphere, having in the third chamber once again passed upwardly through the tobacco.
The prior proposed processes in which particulate tobacco is conveyed in a stream of gaseous medium to dry the tobacco, suffer from one or more of three defects, namely (1) an over-long and continuous exposure of the tobacco to a hot gaseous medium, (2) too intensive a heating regime and (3) after the lapse of a short acceleration period, absence of differentation in the velocity of the tobacco particles and the conveying gaseous medium. The first and second of these defects can have a deleterious effect on the tobacco and on the 5~ 2 final filling power thereof. The third defect resul-ts in a reduced rate of heat ancl mass transfer.
It is an object of the present invention -to provide a method of drying particulate tobacco whereby -the above identified defects of the prior tobacco dryin~J proposals are avoided or at least significantly diminished.
The present invention provides a me-thod of reducing the moisture con-tent of particulate tobacco, wherein particulate tobacco is fed into a stream of hot gaseous medium, said medium conveys said tobacco through a first duct to a first separator, said tobacco is separa-ted from said medium in said first separator, said medium passes from said first separator to a second duct, said tobacco is fed from said first separator into the stream of said medium flowing in said duct downstream of said first separa-tor, whereby said medium conveys said tobacco through said second duc-t to a second separator, and said tobacco is separated from said medium in said second separator.
When particulate -tobacco is treated in accordance with the present invention, the -tobacco is twice subjected to acceleration by the gaseous medium, once in the ~irs-t duct and once in the second duc-t. Intermediate its passage through the first and second ducts the tobacco is maintained for a period out of contac-t with the gaseous medium.
Preferably, delay means is employed to extend this period -to a time value greater than it would otherwise be.
~"2~,2~f-~2 Advantageously, the delay means is adjustable to provide for selection of the residence time of the tobacco particles therein.
Cut stem tobaccos, cut lamina tobaccos or blends thereof may be treated in accordance with the present invention.
The gaseous medium may be, for example, steam, air, steam and air, or nitrogen.
According to another aspect of the present invention there is provided tobacco drying apparatus comprising a first duct, a first gas-flow passage in communication at a downstream end thereof with an upstream end of said first duct, a first tobacco feed path extending to and opening into said first gas-flow passage, first separator means in communication with a downstream end of said first duct, a second duct, a second gas-flow passage in communication at a downstream end thereof with an upstream end of said second duct, a second tobacco feed path extending from said first separator means to and opening into said second gas-flow passage, a gas-flow pipe extending from said first separator means and being in communication with the upstream end of said second gas-flow passage, and second separator means in communication with the downstream end of said second duct, said first separator means being functionable to receive gaseous medium and tobacco from said first duct, to permit said gaseous medium to pass substantially absent said tobacco ~2~ 2 to said gas-flow pipe and to permit said tobacco to pass substantially absent said ~aseous medium to said second tobacco feed path. Pre~erably, variable residence time means is disposed in the second tobacco feed path and is operable to adjust selectively the residence time of tobacco particles in the second feed path.
Apparatus may be provided in accordance with the present invention which apparatus is comparatively inexpensive, compact, simple in construction and readily operable.
In order that the present invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the diagrammatic drawing hereof, which shows a tobacco expansion apparatus.
~5 The tobacco expansion apparatus shown in the dia-grammatic drawing comprises a first tobacco feeder, generally designated 1, which provides a first tobacco feed path. The feeder 1 is comprised of a rotary airlock 2 fitted with an inlet hopper 3 and a downwardly e~tending outlet pipe 4. A feed conveyor 5 is operable to feed particulate tobacco to the inlet hopper 3. At its lower end, the outlet pipe 4 opens into a first gas-flow passage in the form of a short length of piping 6. At an outlet end theeof the piping 6 communicates with an upwardly inclined expansion pipe 7 which provides a first duct.
At its higher end, the pipe 7 opens into the interior of a casing 8 of a first separator 9. Extending ~52~ Z
across the interior of the casing 8, so as to divide the interior into two sections, is a mesh screen 10. A
short outlet pipe 11 extends downwardly from a lowermost location of the separator 9. The pipe 11 serves to intercommunicate that section of the interior of the casing 8 which is to the side of the mesh screen 10 at which the pipe 7 opens into the casing 8, with a second tobacco feeder, generally designated 12.
The second tobacco feeder 12, which provides a second tobacco feed path, is comprised of a rotary airlock 13 and an outlet pipe 14 which e~tends downwardly from the airlock 13 and opens into a second gas-flow passage in the form of a short length of piping 15.
To the side of the mesh screen 10 of the separator 15 9 remote the pipes 7 and 11 a further outlet pipe 16 serves to intercommunicate the interior of the casing 8 with the inlet of a centrifugal fan 17. A gas-flow pipe 18 extends from the outlet of the fan 17 to an inlet end of the piping 15.
The outlet end of the piping 15 communicates with an upwardly inclined expansion pipe 19 which provides a second duct.
At its higher end, the pipe 19 opens into the interior of a casing 20 of a second separator 21. The separator 21 is of similar construction to the separator 9 and comprises a mesh screen 22 dividing the interior of the casing 20 into two sections, a short outlet pipe S~ 2 23 to the same side of the mesh 22 as is the opening of the pipe 19, and a further outlet pipe 24 to the other side of the mesh screen 22. The outlet pipe 23 serves to intercommunicate the interior of the casing 20 with a rotary airlock 25 from which there downwardly extends a discharge pipe 26.
The outlet pipe 24 serves to intercommunicate the interior of the casing 20 of the separator 21 with the inlet of a centrifugal fan 27. From the outlet of the fan 27 a pipe 28 extends, first downwardly and then horizontally, to a heater 29. An e~haust pipe 30 branches from the pipe 28 and a steam make-up pipe 31 communicates with the pipe 28 at a location intermediate the branching location of the pipe 30 and the heater 29.
The heater 29, which may, -for e~ample, be gas or oil fired, is operable to heat the steam/air mixture (hereinafter referred to a~ "gaseous medium") delivered from the pipe 2~. An outlet pipe 32 serves to convey gaseous medium which has been heated in the heater 29 to the inlet end of the piping 6.
In operation of the apparatus to expand particulate tobacco, cut stem tobacco for e~ample, gaseous medium flow is established in the apparatus aided by operation of the centrifugal fans 17 and 27. The tobacco is fed to the inlet hopper 3 from the feed conveyor 5 and passes through the rotary airlock 2, driven by rotary drive means (not shown), and the outlet pipe 4 to the piping 6.
In the piping 6 the tobacco particles are entrained by-the gaseous medium which is conveyed -to the piping 6 in the pipe 32 extending from the heater 29. It is preferable, in order to promote the entrainment of the tobacco particles, for the interior of the piping 6 to be of a venturi configurat:ion with the pipe 4 opening at the throat thereof.
The gasous medium conveys the tobacco particles along the pipe 7 to the first separator 9, the mesh screen 10 of which permits passage of the gaseous medium to the fan 17 but constrains the tobacco particles to pass down-wardly to the air~ock 13. The tobacco passas through the airlock 13, driven by rotary drive means (not shown), and through the outlet pipe 14 to the piping 1~5. In the piping 15 the tobacco particles are entrained by gaseous medium which is conveyed to the piping 15, preferably without the gaseous medium being subjected to re-heating, in the gas-flow pipe 18 extending from the fan 17.
The gaseous medium conveys the tobacco particles along the pipe 19 to the second separator 21, the mesh screen 22 of which permits passage of the gaseous medium to the fan 27 but constrains the tobacco particles to pass downwardly to the airlock 25, driven by rotary drive means (not shown). The tobacco particles pass from the airlock 25 through the discharge pipe 26 to a receptacle or a conveyor (not shown). The tobacco particles are subsequently subjected to a coolin~ step ~L~52~
which is in accordance with established practice and which, for the sake of simplicity, is not further discussed.
From the fan 27 the gaseous medium passes along the pipe 28 to the heater 29 in which the heat given up by the gaseous medium during -the passage thereof through the apparatus is replaced. Gases and water vapour generated in the apparatus and air which has entered the apparatus through the airlocks 2~ 13 and 25 are removed via the exhaust pipe 30. Make-up steam can be supplied, from a steam generator (not shown), via the make-up pipe 31.
The apparatus which is comparatively inexpensive, compact and simple in construction and operation, provides a very efficient means of drying and expanding particulate tobacco. As soon as the tobacco enters the p,ping 6, the tobacco particles are accelerated by the gaseous medium.
Thus as the particles are conveyed up the pipe 7 by the gaseous medium, the velocity differential between the tobacco particles and the gaseous medium diminishes.
However, the separation of the tobacco and the gaseous medium effected in the separator 9 and the reintroduction of the tobacco into the gaseous medium in piping 15 means that the process of acceleration of the tobacco is repeated. This means that there is a velocity differential between the tobacco and the gaseous medium over a greater period of time than would be the case if the tobacco ~2~2 passed along a single, straight expansion pipe, of a length equivalent to the combined lengths of pipes 7 and 19, without an intermediate reacceleration. Thus in comparison with an apparatus comprising a single expansion pipe of equivalent length, the apparatus shown in the drawing effects heat and mass transfer at enhanced efficiency levels.
Moreover, the separation of the tobacco particles from the hot gaseous medium intermediate the passage of the particles in contact with the medium in the first and second expansion pipes 7, 19 permits a degree of moisture migration to take place in each particle towards the surface of the particle and ensures that the rigour of the heating regime to which the particles are subjected is less than would otherwise be the case. This has benefits in terms of the filling power of the tobacco which passes from the apparatus through discharge pipe 26.
In order to obtain adjustment of the residence time of the tobacco in the airlock 13, the drive means thereof is preferably of a variable speed type.
In order to minimise the overall time during which the tobacco is in contact with the hot gaseous medium, which overall time may be, for example, of the order of one second, it is important that the mean residence time of the tobacco particles in the separators is short and that there is only a narrow statistical distribution of residence times of the particles in the separators.
.~ 252~
This requirement is met by the separators 9 and 21 which are of a type supplied by Hambro Machinery Limited, Nottingham, England. Cyclone separators would meet the requirement less well.
Although, as above described, the apparatus is - operated without re-heating of the gaseous medium in its passage from the fan 17 to the piping 16, it is conceiv-able to provide such a re-heating step.
As an alternative to the tobacco passing via the pipe 14 directly from the airlock 13 to the piping 15, it may be fed from the airlock 13 onto a conveyor (not shown), from which the tobacco passes into the piping 15 through a further airlock (not shown). In such case the conveyor and/or the further airlock can provide a delay function in addition to, or in place of, that of the airlock 13. The conveyor and/or the further airlock may be provided with variable speed drive means.
Claims (10)
1. A method of reducing the moisture content of particulate tobacco wherein particulate tobacco is fed into a stream of hot gaseous medium, said medium conveys said tobacco through a first duct to a first separator, said tobacco is separated from said medium in said first separator, said medium passes from said first separator to a second duct, said is fed from said into the stream of said medium flowing in said second duct downstream of said first separator, whereby said medium conveys said tobacco through said second duct to a second separator, and said tobacco is separated from said medium in said second separator.
2. A method according to Claim 1, wherein after said medium has passed from said first separator but before said medium re-encounters said tobacco, said medium is heated.
3. A method according to Claim 1, wherein said tobacco, after passing from said first separator and before re-encountering said medium, is subjected to flow delay.
4. A method according to Claim 1, 2 or 3, wherein the filling power of said tobacco at exit from said second separator is greater than the filling power of said tobacco when fed into said stream of gaseous medium upstream of said first separator.
5. Tobacco drying apparatus comprising a first duct, a first gas-flow passage in communication at a downstream end thereof with an upstream end of said first duct, a first tobacco feed path extending to and opening into said first gas-flow passage, first separator means in communication with a downstream end of said first duct, a second duct, a second gas-flow passage in communication at a downstream end thereof with an upstream end of said second duct, a second tobacco feed path extending from said first separator means to and opening into said second gas-flow passage, a gas-flow pipe extending from said first separator means and being in communication with the upstream end of said second gas-flow passage, and second separator means in communication with the downstream end of said second duct, said first separator means being functionable to receive gaseous medium and tobacco from said first duct, to permit said gaseous medium to pass substantially absent said tobacco to said gas-flow pipe and to permit said tobacco to pass substantially absent said gaseous medium to said second feed path.
6. Apparatus according to Claim 5, wherein said second feed path comprises flow delay means.
7. Apparatus according to Claim 6, wherein said delay means is adjustable to provide for selection of residence time of said tobacco therein.
8. Apparatus according to Claim 6 or 7, wherein said delay means comprises an airlock.
9. Apparatus according to Claim 5, and further comprising heating means operable to heat gaseous medium in said gas-flow pipe.
10. Apparatus according to Claim 5, and further comprising supply means operable to supply hot gaseous medium to said first gas-flow passage at the upstream end thereof.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8515217 | 1985-06-15 | ||
| GB858515217A GB8515217D0 (en) | 1985-06-15 | 1985-06-15 | Treatment of tobacco |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1252012A true CA1252012A (en) | 1989-04-04 |
Family
ID=10580813
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000511538A Expired CA1252012A (en) | 1985-06-15 | 1986-06-13 | Treatment of tobacco |
| CA000511537A Expired CA1253412A (en) | 1985-06-15 | 1986-06-13 | Expansion of tobacco |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000511537A Expired CA1253412A (en) | 1985-06-15 | 1986-06-13 | Expansion of tobacco |
Country Status (21)
| Country | Link |
|---|---|
| US (2) | US4693264A (en) |
| JP (2) | JPH0789898B2 (en) |
| AU (2) | AU576156B2 (en) |
| BE (2) | BE904918A (en) |
| BR (2) | BR8602835A (en) |
| CA (2) | CA1252012A (en) |
| CH (2) | CH667975A5 (en) |
| DE (2) | DE3619816C2 (en) |
| DK (2) | DK278086A (en) |
| ES (2) | ES8800016A1 (en) |
| FI (2) | FI862500L (en) |
| GB (3) | GB8515217D0 (en) |
| HK (1) | HK96991A (en) |
| IN (2) | IN167447B (en) |
| IT (2) | IT1190003B (en) |
| MX (1) | MX163894B (en) |
| MY (2) | MY100076A (en) |
| NL (2) | NL8601444A (en) |
| NZ (2) | NZ216510A (en) |
| SG (1) | SG76491G (en) |
| ZA (2) | ZA864026B (en) |
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| FR2608019B1 (en) * | 1986-12-11 | 1991-01-25 | Decoufle Sarl | AIR GUIDANCE SYSTEM FOR A MACHINE FOR MAKING CORD-LIKE ARTICLES FROM THE TOBACCO PROCESSING INDUSTRY |
| GB8630656D0 (en) * | 1986-12-22 | 1987-02-04 | British American Tobacco Co | Expansion of particulate vegetable material |
| IE870154L (en) * | 1987-01-21 | 1988-07-21 | Bord Na Mona | Peat drying apparatus |
| DE3710677A1 (en) * | 1987-03-31 | 1988-10-13 | Bat Cigarettenfab Gmbh | DEVICE FOR EXPANDING CRUSHED TOBACCO MATERIAL |
| GB8712618D0 (en) * | 1987-05-28 | 1987-07-01 | British American Tobacco Co | Expansion of tobacco |
| CA1328064C (en) * | 1987-07-27 | 1994-03-29 | Masao Kobari | Apparatus for expanding material for foodstuffs, favorite items and the like |
| DE3878072D1 (en) * | 1987-07-29 | 1993-03-18 | Bat Cigarettenfab Gmbh | SEPARATOR FOR SEPARATING TOBACCO PARTICLES FROM A TOBACCO / GAS MIXTURE. |
| US4895174A (en) * | 1988-05-19 | 1990-01-23 | R. J. Reynolds Tobacco Company | Tobacco particle separator |
| US5165426A (en) * | 1989-08-18 | 1992-11-24 | British-American Tobacco Company Limited | Processing of tobacco leaves |
| US5251649A (en) * | 1991-06-18 | 1993-10-12 | Philip Morris Incorporated | Process for impregnation and expansion of tobacco |
| DE4127374A1 (en) * | 1991-08-19 | 1993-02-25 | Hauni Werke Koerber & Co Kg | DEVICE FOR CONVERTING TOBACCO PARTS INTO A POWER DRYER |
| CH683226A5 (en) * | 1991-12-09 | 1994-02-15 | Egri Laszlo | Expanding and drying tobacco. |
| DE4221573A1 (en) * | 1992-07-01 | 1994-01-05 | Hauni Werke Koerber & Co Kg | Method and arrangement for drying tobacco |
| SK139993A3 (en) * | 1992-12-17 | 1994-09-07 | Philip Morris Prod | Method of impregnation and expanding of tobacco and device for its performing |
| AU5752594A (en) * | 1993-04-20 | 1994-11-03 | Deere & Company | Air separation tube for a pneumatic delivery system |
| GB9322967D0 (en) * | 1993-11-08 | 1994-01-05 | Gbe International Plc | A process and apparatus for treating a hygroscopic material |
| US5582193A (en) * | 1994-08-24 | 1996-12-10 | Philip Morris Incorporated | Method and apparatus for expanding tobacco |
| US5908032A (en) * | 1996-08-09 | 1999-06-01 | R.J. Reynolds Tobacco Company | Method of and apparatus for expanding tobacco |
| GB2367352A (en) * | 2000-09-28 | 2002-04-03 | Dickinson Legg Ltd | Air leakage elimination for continuous stream dryers |
| CN100389689C (en) * | 2001-11-26 | 2008-05-28 | 日本烟草产业株式会社 | Granular material air dryer |
| US7556047B2 (en) * | 2003-03-20 | 2009-07-07 | R.J. Reynolds Tobacco Company | Method of expanding tobacco using steam |
| RU2305476C1 (en) * | 2006-03-20 | 2007-09-10 | Олег Иванович Квасенков | Method for producing of aromatized swollen tobacco |
| RU2305477C1 (en) * | 2006-03-20 | 2007-09-10 | Олег Иванович Квасенков | Method for producing of aromatized swollen tobacco |
| RU2306786C1 (en) * | 2006-03-23 | 2007-09-27 | Олег Иванович Квасенков | Method for increasing of tobacco volume |
| RU2306789C1 (en) * | 2006-03-24 | 2007-09-27 | Олег Иванович Квасенков | Method for producing of tobacco with increased filling capacity |
| RU2306031C1 (en) * | 2006-03-24 | 2007-09-20 | Олег Иванович Квасенков | Method for producing of aromatized tobacco with increased filling capacity |
| RU2306036C1 (en) * | 2006-03-27 | 2007-09-20 | Олег Иванович Квасенков | Method for producing of aromatized tobacco with increased filling capacity |
| RU2445560C1 (en) * | 2010-08-18 | 2012-03-20 | Государственное научное учреждение Всероссийский научно-исследовательский институт крахмалопродуктов Российской академии сельскохозяйственных наук | Method for drying high-moisture products and device for its implementation |
| WO2012132008A1 (en) | 2011-03-31 | 2012-10-04 | 日本たばこ産業株式会社 | Tobacco material expansion method and device |
| WO2012132006A1 (en) | 2011-03-31 | 2012-10-04 | 日本たばこ産業株式会社 | Tobacco material expansion method and device |
| PL2929788T3 (en) * | 2014-04-04 | 2018-10-31 | Garbuio S.P.A. | Drying plant for particulate materials |
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| GB402707A (en) * | 1932-08-27 | 1933-12-07 | Paul Rosin | Improvements relating to pneumatic drying devices |
| GB463060A (en) * | 1935-09-20 | 1937-03-22 | Alec Henry Rowles | Improvements relating to the drying and conditioning of cereals and other substances |
| US3580644A (en) * | 1969-03-04 | 1971-05-25 | Brown & Williamson Tobacco Corp | Pneumatic feed system for uniform supply of tobacco to cigarette making machines |
| GB1575175A (en) * | 1978-05-05 | 1980-09-17 | Hambro Machinery Ltd | Separation apparatus |
| US4308876A (en) * | 1979-02-16 | 1982-01-05 | Airco, Inc. | Methods and apparatus for expanding tobacco |
| US4366825A (en) * | 1979-11-21 | 1983-01-04 | Philip Morris Incorporated | Expansion of tobacco |
| US4301819A (en) * | 1980-04-11 | 1981-11-24 | Brown & Williamson Tobacco Corporation | Apparatus for prevention of material build-up such as tobacco in a conduit |
| DE3147846C2 (en) * | 1981-09-05 | 1984-07-19 | B.A.T. Cigaretten-Fabriken Gmbh, 2000 Hamburg | Process for improving the filling capacity of tobacco material |
| US4625736A (en) * | 1981-09-23 | 1986-12-02 | Rothchild Ronald D | Method and apparatus for expanding tobacco with water |
| US4407306A (en) * | 1981-12-17 | 1983-10-04 | American Brands, Inc. | Method for expanding tobacco with steam at high temperature and velocity |
| GB8315988D0 (en) * | 1983-06-10 | 1983-07-13 | British American Tobacco Co | Recordering of tobacco |
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| BR8405828A (en) * | 1983-11-16 | 1985-09-17 | Brown & Williamson Tobacco Corp | PROCESS TO PRODUCE A CONTENT IN EXPANDED TOBACCO MOISTURE |
-
1985
- 1985-06-15 GB GB858515217A patent/GB8515217D0/en active Pending
-
1986
- 1986-03-05 GB GB08605376A patent/GB2176385B/en not_active Expired
- 1986-05-29 ZA ZA864026A patent/ZA864026B/en unknown
- 1986-05-30 IN IN426/MAS/86A patent/IN167447B/en unknown
- 1986-05-30 IN IN427/MAS/86A patent/IN167541B/en unknown
- 1986-06-04 NL NL8601444A patent/NL8601444A/en not_active Application Discontinuation
- 1986-06-06 NL NL8601484A patent/NL8601484A/en not_active Application Discontinuation
- 1986-06-09 IT IT20718/86A patent/IT1190003B/en active
- 1986-06-09 IT IT20719/86A patent/IT1190004B/en active
- 1986-06-10 AU AU58519/86A patent/AU576156B2/en not_active Expired
- 1986-06-10 AU AU58518/86A patent/AU577020B2/en not_active Ceased
- 1986-06-11 FI FI862500A patent/FI862500L/en not_active Application Discontinuation
- 1986-06-11 FI FI862501A patent/FI862501A7/en not_active Application Discontinuation
- 1986-06-11 BR BR8602835A patent/BR8602835A/en not_active IP Right Cessation
- 1986-06-11 BR BR8602834A patent/BR8602834A/en not_active IP Right Cessation
- 1986-06-12 CH CH2380/86A patent/CH667975A5/en not_active IP Right Cessation
- 1986-06-12 JP JP61137233A patent/JPH0789898B2/en not_active Expired - Lifetime
- 1986-06-12 NZ NZ216510A patent/NZ216510A/en unknown
- 1986-06-12 JP JP61137232A patent/JPS623778A/en active Pending
- 1986-06-12 NZ NZ216509A patent/NZ216509A/en unknown
- 1986-06-12 GB GB08614300A patent/GB2176584B/en not_active Expired
- 1986-06-12 DE DE3619816A patent/DE3619816C2/en not_active Expired - Lifetime
- 1986-06-12 CH CH2381/86A patent/CH669496A5/fr not_active IP Right Cessation
- 1986-06-12 DE DE19863619815 patent/DE3619815A1/en not_active Withdrawn
- 1986-06-13 ES ES556023A patent/ES8800016A1/en not_active Expired
- 1986-06-13 US US06/873,989 patent/US4693264A/en not_active Expired - Fee Related
- 1986-06-13 BE BE0/216779A patent/BE904918A/en not_active IP Right Cessation
- 1986-06-13 CA CA000511538A patent/CA1252012A/en not_active Expired
- 1986-06-13 CA CA000511537A patent/CA1253412A/en not_active Expired
- 1986-06-13 US US06/874,020 patent/US4697604A/en not_active Expired - Lifetime
- 1986-06-13 BE BE0/216780A patent/BE904919A/en not_active IP Right Cessation
- 1986-06-13 MX MX2805A patent/MX163894B/en unknown
- 1986-06-13 ES ES556024A patent/ES8801574A1/en not_active Expired
- 1986-06-13 DK DK278086A patent/DK278086A/en not_active Application Discontinuation
- 1986-06-13 DK DK278186A patent/DK278186A/en not_active Application Discontinuation
- 1986-11-29 ZA ZA864025A patent/ZA864025B/en unknown
-
1987
- 1987-08-13 MY MYPI87001332A patent/MY100076A/en unknown
- 1987-08-13 MY MYPI87001333A patent/MY100172A/en unknown
-
1991
- 1991-09-13 SG SG764/91A patent/SG76491G/en unknown
- 1991-11-28 HK HK969/91A patent/HK96991A/en not_active IP Right Cessation
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